Search results for "Ribosome"

Symptom severity, infection progression and plant responses in solanum plants caused by three pospiviroids vary with the inoculation procedure

2021

This article belongs to the Section Molecular Plant Sciences.

Mitochondrial bioenergetic pathways in blood leukocyte transcriptome decrease after intensive weight loss but are rescued following weight regain in …

2021

Prolonged periods of energy deficit leading to weight loss induce metabolic adaptations resulting in reduced energy expenditure, but the mechanisms for energy conservation are incompletely understood. We examined 42 healthy athletic females (age 27.5 +/- 4.0 years, body mass index 23.4 +/- 1.7 kg/m(2)) who volunteered into either a group dieting for physique competition (n = 25) or a control group (n = 17). The diet group substantially reduced their energy intake and moderately increased exercise levels to induce loss of fat mass that was regained during a voluntary weight regain period. The control group maintained their typical lifestyle habits and body mass as instructed. From the diet g…

2018

RNA-binding proteins (RBPs) establish the cellular fate of a transcript, but an understanding of these processes has been limited by a lack of identified specific interactions between RNA and protein molecules. Using MS2 RNA tagging, we have purified proteins associated with individual mRNA species induced by osmotic stress, STL1 and GPD1. We found members of the Lsm1-7/Pat1 RBP complex to preferentially bind these mRNAs, relative to the non-stress induced mRNAs, HYP2 and ASH1. To assess the functional importance, we mutated components of the Lsm1-7/Pat1 RBP complex and analyzed the impact on expression of osmostress gene products. We observed a defect in global translation inhibition under…

Yeast Cth2 protein represses the translation of ARE-containing mRNAs in response to iron deficiency

2018

In response to iron deficiency, the budding yeast Saccharomyces cerevisiae undergoes a metabolic remodeling in order to optimize iron utilization. The tandem zinc finger (TZF)-containing protein Cth2 plays a critical role in this adaptation by binding and promoting the degradation of multiple mRNAs that contain AU-rich elements (AREs). Here, we demonstrate that Cth2 also functions as a translational repressor of its target mRNAs. By complementary approaches, we demonstrate that Cth2 protein inhibits the translation of SDH4, which encodes a subunit of succinate dehydrogenase, and CTH2 mRNAs in response to iron depletion. Both the AREs within SDH4 and CTH2 transcripts, and the Cth2 TZF are es…

The exonuclease Xrn1 activates transcription and translation of mRNAs encoding membrane proteins

2019

The highly conserved 5’–3’ exonuclease Xrn1 regulates gene expression in eukaryotes by coupling nuclear DNA transcription to cytosolic mRNA decay. By integrating transcriptome-wide analyses of translation with biochemical and functional studies, we demonstrate an unanticipated regulatory role of Xrn1 in protein synthesis. Xrn1 promotes translation of a specific group of transcripts encoding membrane proteins. Xrn1-dependence for translation is linked to poor structural RNA contexts for translation initiation, is mediated by interactions with components of the translation initiation machinery and correlates with an Xrn1-dependence for mRNA localization at the endoplasmic reticulum, the trans…

2017

Reconstructing the transition from a single compartment bacterium to a highly compartmentalized eukaryotic cell is one of the most studied problems of evolutionary cell biology. However, timing and details of the establishment of compartmentalization are unclear and difficult to assess. Here, we propose the use of molecular markers specific to cellular compartments to set up a framework to advance the understanding of this complex intracellular process. Specifically, we use a protein family related to ribosome biogenesis, YRG (YlqF related GTPases), whose evolution is linked to the establishment of cellular compartments, leveraging the current genomic data. We analyzed orthologous proteins …

Conserved Organisation of 45S rDNA Sites and rDNA Gene Copy Number among Major Clades of Early Land Plants

2016

Genes encoding ribosomal RNA (rDNA) are universal key constituents of eukaryotic genomes, and the nuclear genome harbours hundreds to several thousand copies of each species. Knowledge about the number of rDNA loci and gene copy number provides information for comparative studies of organismal and molecular evolution at various phylogenetic levels. With the exception of seed plants, the range of 45S rDNA locus (encoding 18S, 5.8S and 26S rRNA) and gene copy number variation within key evolutionary plant groups is largely unknown. This is especially true for the three earliest land plant lineages Marchantiophyta (liverworts), Bryophyta (mosses), and Anthocerotophyta (hornworts). In this work…

Human peroxin PEX3 is co-translationally integrated into the ER and exits the ER in budding vesicles

2015

The long-standing paradigm that all peroxisomal proteins are imported post-translationally into pre-existing peroxisomes has been challenged by the detection of peroxisomal membrane proteins (PMPs) inside the endoplasmic reticulum (ER). In mammals, the mechanisms of ER entry and exit of PMPs are completely unknown. We show that the human PMP PEX3 inserts co-translationally into the mammalian ER via the Sec61 translocon. Photocrosslinking and fluorescence spectroscopy studies demonstrate that the N-terminal transmembrane segment (TMS) of ribosome-bound PEX3 is recognized by the signal recognition particle (SRP). Binding to SRP is a prerequisite for targeting of the PEX3-containing ribosome•n…

Muscle and serum metabolomes are dysregulated in colon-26 tumor-bearing mice despite amelioration of cachexia with activin receptor type 2B ligand bl…

2019

Cancer-associated cachexia reduces survival, which has been attenuated by blocking the activin receptor type 2B (ACVR2B) ligands in mice. The purpose of this study was to unravel the underlying physiology and novel cachexia biomarkers by use of the colon-26 (C26) carcinoma model of cancer cachexia. Male BALB/c mice were subcutaneously inoculated with C26 cancer cells or vehicle control. Tumor-bearing mice were treated with vehicle (C26+PBS) or soluble ACVR2B either before (C26+sACVR/b) or before and after (C26+sACVR/c) tumor formation. Skeletal muscle and serum metabolomics analysis was conducted by gas chromatography-mass spectrometry. Cancer altered various biologically functional groups …

Ribosome-Targeting Antibiotics Impair T Cell Effector Function and Ameliorate Autoimmunity by Blocking Mitochondrial Protein Synthesis

2019

Summary While antibiotics are intended to specifically target bacteria, most are known to affect host cell physiology. In addition, some antibiotic classes are reported as immunosuppressive for reasons that remain unclear. Here, we show that Linezolid, a ribosomal-targeting antibiotic (RAbo), effectively blocked the course of a T cell-mediated autoimmune disease. Linezolid and other RAbos were strong inhibitors of T helper-17 cell effector function in vitro, showing that this effect was independent of their antibiotic activity. Perturbing mitochondrial translation in differentiating T cells, either with RAbos or through the inhibition of mitochondrial elongation factor G1 (mEF-G1) progressi…